Ionic and nonionic species in (CH3)4NF·mHF melts (m = 3.0−5.0) were investigated by 1H NMR, IR spectroscopy, Raman spectroscopy, and high-energy X-ray diffraction measurements. Three types of anions, (FH)F-, (FH)2F-, and (FH)3F-, were identified in these melts. The (FH)2F- anion was thermodynamically the most stable of the complex anions in the (CH3)4NF·mHF (3.0 ≤ m ≤ 5.0), and its concentration was the highest. (FH) x F- anions with x = 4 and 5 were not present at room temperature though the presence of (FH) x F- (x = 1−5) has been known in the solid-state crystals. In the (CH3)4NF·mHF melts with m = 3.0−5.0, the number of HF combined with F- is three or less, and excess HF exists as molecular HF.

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Surface fluorination of TiO2(B) powder was conducted by pure F2 gas at room temperature for 1 h and the effect on the charge/discharge properties was examined as a negative electrode of Li-ion batteries (LIBs). X-ray diffraction (XRD) pattern was not changed before and after the surface fluorination though the peak intensities became weaker than that of the pristine sample, indicating the etching of the surface of SF-TiO2(B) power. This was supported by scanning electron microscopy (SEM) observation. However, X-ray photoelectron spectroscopy (XPS) analysis clearly revealed that F atoms exist on the surface of TiO2(B) particles and probably were covalently bonded with Ti atoms near the surface. From the charge/discharge tests at a C/6 rate, the SF-TiO2(B) exhibited a higher 1st discharge (203 mAh g-1) than the pristine sample (181 mAh g-1) with a good cycleability. Impedance analysis revealed that both resistances of solid electrolyte interphase (SEI) film and charge transfer at the SEI /active material interface were reduced by surface fluorination, implying the improvement of SEI film and permeability of the electrolyte solution to the interphase. The rate capability was improved by the surface fluorination up to 1C rate, at which the SF-TiO2(B) exhibited a high discharge capacity of around 150 mAh g-1.

LiNiO 2 -coated Ni sheet anodes were prepared by a sol-gel coating method and an atmospheric plasma-spraying technique, and were used in electrolytic production of ͑CF 3 ͒ 3 N in a room-temperature molten fluoride ͑CH 3 ͒ 4 NF·4.0HF. Li x Ni 2−x O 2 thin films of x = 0.6-0.8 were successfully formed on Ni sheets by the sol-gel coating methods. The LiNiO 2 film prepared by atmospheric plasma-spraying technique had nearly the stoichiometric composition ͑x Ϸ 1͒. These LiNiO 2 -coated Ni sheet anodes gave lower anode potentials than pure Ni anode during electrolysis, because the presence of the LiNiO 2 layer suppressed the formation of NiF 2 insulation layer and the electronic conductivity of the former was much higher than that of the latter. The maximum mole fraction of ͑CF 3 ͒ 3 N of 33% in the anode gas was obtained in electrolysis using the plasma-sprayed LiNiO 2 -coated Ni sheet anode at 20 mA cm −2 in the ͑CH 3 ͒ 4 NF·4.0HF melt. The anodic potential under the above conditions was 4.13 V after electrolysis for 100 h, which was the lowest of all experiments. Consequently, stoichiometric LiNiO 2 -coated Ni sheet was the most preferable anode material for the electrolytic ͑CF 3 ͒ 3 N synthesis in the ͑CH 3 ͒ 4 NF·4.0HF melt.Perfluoroalkyl group, −CF 3 , promotes lipophilicity of organic compounds, and therefore perfluorotrimethylamine, ͑CF 3 ͒ 3 N, is an important fluorine source for synthesis of useful organic fluorocompounds as medicines and agricultural chemicals, because it easily decomposes to release CF 3 radicals. ͑CF 3 ͒ 3 N is also expected as a new dry etchant for microfabrication of SiO wafers. In addition, Fukaya et al. reported that ͑CF 3 ͒ 3 N is a potential fire extinguishing gas from ab initio calculation. 1,2 A room-temperature molten fluoride ͑CH 3 ͒ 4 NF·mHF melt ͑3.5 ഛ m ഛ 5.0; m.p.: 25 and −70°C for m = 3.5 and 5.0, respectively͒ is expected to be a useful electrolyte for electrochemical fluorination because of its high ionic conductivity ͓e.g., 196.7 mS cm −1 at 25°C for ͑CH 3 ͒ 4 NF·4.0HF͔ 3 . Perfluorotrimethylamine, ͑CF 3 ͒ 3 N, can be synthesized by electrochemical perfluorination of ͑CH 3 ͒ 4 N + cation in the melt, and hence it is a new process that can replace the Simons process, in which trimethylamine, ͑CH 3 ͒ 3 N, dissolved in anhydrous HF is electrolyzed using Ni anode. 4-6 In the Simons process, the temperature of the electrolyte should be kept under 0°C to prevent the vaporization of HF during electrolysis, and the electrolytic cell should be equipped with a cooling tube to condense gaseous HF in the anode gas. In contrast, our process is free from such problems because the vapor pressure of HF on the ͑CH 3 ͒ 4 NF·mHF melts is low. Furthermore, the fluorination reaction of organic compounds in our process occurs by chemical reaction of atomic fluorine generated electrochemically in addition to the indirect fluorination reaction by electrochemically formed NiF 3 in the Simons process. 4,6 However, our previous studies revealed that Ni anode cannot be used in pure ͑CH 3 ͒ 4 NF·4.0...